A gear device includes a first gear, a second gear, and a third gear. The second gear is constituted of first meshing teeth that mesh with teeth in a first row of teeth of the first gear, second meshing teeth that mesh with teeth in a second row of teeth of the first gear, third meshing teeth that mesh with teeth in a third row of teeth of the third gear, and fourth meshing teeth that mesh with teeth in a fourth row of teeth of the third gear. The helix directions of the first meshing teeth and the third meshing teeth are the same direction. The helix directions of the second meshing teeth and the fourth meshing teeth are the same direction.

A gear drive system is provided having a first gear and a second gear. The second gear has a first peripheral portion and a second peripheral portion. A first set of gear teeth can be defined peripherally over the first peripheral portion and/or the second peripheral portion. The first peripheral portion and/or the second peripheral portion can be more resilient, resulting in a first backlash between the first set of gear teeth and the teeth of the first gear, less than a second backlash between the second set of gear teeth and the teeth of the first gear. Each gear tooth of the second gear can have a gear tooth spacing between adjacent gear teeth. The gear tooth spacing over the first peripheral portion and/or the second peripheral portion can be less than the gear tooth spacing at portions other than the first peripheral portion and/or the second peripheral portion.

A planetary gear mechanism includes a plurality of planetary gear units each including a sun gear member to be rotationally driven by a driving source, an internal gear member, planetary gear members, and a carrier member, and a case body that internally houses the planetary gear units and includes an inner circumferential surface to be brought into surface contact with outer circumferential surfaces of the internal gear members. Engagement portions having concave shapes or convex shapes that can be fitted to convex shapes or concave shapes formed in the outer circumferential surfaces of the internal gear members are formed in the inner circumferential surface of the case body. The engagement portions are engaged with the convex shapes provided in the outer circumferential surfaces of the internal gear members, from an opposite direction to a rotating direction of the carrier members, to thereby inhibit the internal gear members from rotating.

A gear assembly that includes a cutting gear having an outer edge and an inner edge, wherein a plurality of gear teeth is formed on the outer edge thereof; and an internal gear having an outer edge and an inner edge. The internal gear further includes a plurality of gear teeth formed on the inner edge thereof, wherein the gear teeth formed on the inner edge of the internal gear are adapted to engage the gear teeth formed on the outer edge of the cutting gear; a plurality of troughs, wherein each trough in the plurality of troughs is formed between two of the gear teeth formed on the inner edge of the internal gear; and a plurality of debris discharge channels, wherein each debris discharge channel is formed at the bottommost portion of each trough and extends away from the trough toward the outer edge of the internal gear.

A cam assembly having a solid cylindrical with a near end and a distal end and an opening extending from the near end through the distal end, wherein the opening is circular in configuration and has an inset, the near end is configured at a slight angle of less than about 15 from the vertical, and the opening extending from the near end through the distal end is angled through the cam assembly, the opening beginning at the near end and near a bottom edge of the solid cylinder and terminating through the distal end near a top edge of the solid cylinder.

Examples are provided that describe a cycloid transmission with a chain link ring. An example cycloid transmission includes a motor shaft attached to a disc. The motor shaft may be used for rotating the disc. The cycloid transmission also comprises an outer chain link ring that surrounds the disc. The outer chain link ring includes rollers that are inserted at given interfaces between links of the outer chain link ring. The rollers contact the disc as the disc rotates. The cycloid transmission also comprises a housing. The links of the outer chain link are coupled at the given interfaces. The rollers are inserted at the given interfaces and into the housing.

An internal gear includes plural teeth each including an addendum area, a dedendum area, and an intermediate area including a protrusion and a recessed portion. The intermediate area includes a first border position provided at a position between the protrusion and the recessed portion, a second border position provided at a position between the intermediate area and the dedendum area, a third border position provided at a position between the intermediate area and the addendum area, a first average radius provided from the first border position to the second border position, and a second average radius provided from the first border position to the third border position. The first average radius is smaller than the second average radius. The addendum area includes a first curvature radius provided at a first center position in a tooth thickness direction, the first curvature radius being set at a maximum.

A ring gear for an aircraft mechanical gearbox, the ring gear having an annular shape about an axis and having an internal toothing at its internal periphery, an external annular flange or splines at its external periphery, and an annular web extending between the internal toothing and the external flange or splines. The web can include an annular row of arms which are distributed about the axis, these arms connecting the internal toothing to the external flange or splines and being formed in a single piece with the internal toothing and the external flange or splines.

An in-wheel drive device includes: a wheel bearing including a hub and an outer race spaced apart outward in a radial direction from the hub; and a speed reducer including a ring gear coupled to the wheel bearing. An outer surface of the ring gear, in the radial direction, and an inner surface of the wheel bearing, in the radial direction, adjoin to define first and second regions. The ring gear includes a protruding portion disposed on the outer surface of the ring gear in the second region and having a shape protruding toward the inner surface of the wheel bearing. The wheel bearing includes a recessed portion disposed on the inner surface of the wheel bearing in the second region and having a shape corresponding to a shape of the protruding portion. The protruding portion and the recessed portion engage each other in the second region.

A gear includes an annular sleeve and a tooth portion provided by injection molding to cover a part of the sleeve. The sleeve is a stacked body including a plurality of annular steel plates stacked in an axial direction of the sleeve.